What are the dissolution methods of hydroxypropyl methylcellulose HPMC?

1. What are the dissolution methods of hydroxypropyl methylcellulose HPMC?

Answer: Hot water dissolution method: Since HPMC does not dissolve in hot water, HPMC can be evenly dispersed in hot water at the initial stage, and then quickly dissolves when cooled. Two typical methods are described as follows:

1), add 1/3 or 2/3 of the required amount of water into the container, and heat it to 70°C, disperse HPMC according to the method of 1), and prepare hot water slurry; then add the remaining amount of cold water to hot water slurry, the mixture was cooled after stirring.

Powder mixing method: mix HPMC powder with a large amount of other powdery substances, mix thoroughly with a mixer, and then add water to dissolve, then HPMC can be dissolved at this time without agglomeration, because there is only a little HPMC in every tiny corner Powder, will dissolve immediately when in contact with water. ——Putty powder and mortar manufacturers are using this method. [Hydroxypropyl methylcellulose (HPMC) is used as a thickener and water retention agent in putty powder mortar.

2) Put the required amount of hot water into the container and heat it to about 70°C. The hydroxypropyl methylcellulose was gradually added under slow stirring, initially the HPMC floated on the surface of the water, and then gradually formed a slurry, which was cooled under stirring.

2. There are several types of hydroxypropyl methylcellulose HPMC. What are the differences in their uses?

Answer: Hydroxypropyl methylcellulose HPMC can be divided into instant type and hot-dissolution type. Instant type products disperse rapidly in cold water and disappear into the water. At this time, the liquid has no viscosity, because HPMC is only dispersed in water, there is no real dissolve. About 2 minutes, the viscosity of the liquid gradually increases, forming a transparent viscous colloid. Hot-melt products, when met with cold water, can disperse quickly in hot water and disappear in hot water. When the temperature drops to a certain temperature, the viscosity will slowly appear until it forms a transparent viscous colloid. The hot-melt type can only be used in putty powder and mortar. In liquid glue and paint, there will be grouping phenomenon and cannot be used. The instant type has a wider range of applications. It can be used in putty powder and mortar, as well as liquid glue and paint, without any contraindications.

3. What is the main application of hydroxypropyl methylcellulose (HPMC)?

Answer: HPMC is widely used in construction materials, coatings, synthetic resins, ceramics, medicine, food, textiles, agriculture, cosmetics, tobacco and other industries. HPMC can be divided into: construction grade, food grade and pharmaceutical grade according to usage. At present, most of the domestic products are construction grade. In construction grade, putty powder is used in a large amount, about 90% is used for putty powder, and the rest is used for cement mortar and glue.

4. How to judge the quality of hydroxypropyl methylcellulose (HPMC) simply and intuitively?

Answer: (1) Specific gravity: The larger the specific gravity, the heavier the better. The ratio is large, generally because

(2) Whiteness: Although whiteness cannot determine whether HPMC is easy to use, and if whitening agents are added during the production process, it will affect its quality. However, most of the good products have good whiteness.

(3) Fineness: The fineness of HPMC generally has 80 mesh and 100 mesh, and 120 mesh is less. Most HPMC produced in Hebei is 80 mesh. The finer the fineness, the better it is generally.

(4) Light transmittance: put hydroxypropyl methylcellulose (HPMC) into water to form a transparent colloid, and check its light transmittance. The higher the light transmittance, the better, indicating that there are less insolubles in it. . The permeability of the vertical reactor is generally good, and that of the horizontal reactor is worse, but it does not mean that the quality of the vertical reactor is better than that of the horizontal reactor, and there are many factors to determine the product quality. The content of hydroxypropyl group in it is high, and the content of hydroxypropyl group is high, and the water retention is better.

5. What are the main technical indicators of hydroxypropyl methylcellulose (HPMC)?

Answer: Hydroxypropyl content and viscosity, most users are concerned about these two indicators. Those with high hydroxypropyl content generally have better water retention. High viscosity, water retention, relatively (rather than

6. What is the appropriate viscosity of hydroxypropyl methylcellulose (HPMC)?

Answer: Putty powder is generally 100,000 yuan, and the requirements for mortar are higher, and it is easy to use 150,000 yuan. Moreover, the most important function of HPMC is water retention, followed by thickening. In the putty powder, as long as the water retention is good and the viscosity is low (70,000-80,000), it is also possible. Of course, the higher the viscosity, the better the relative water retention. When the viscosity exceeds 100,000, the viscosity will affect the water retention. Not much anymore. Absolutely) is also better, and the viscosity is higher, and it is better to use in cement mortar.

7. What are the main raw materials of hydroxypropyl methylcellulose (HPMC)?

Answer: The main raw materials of hydroxypropyl methylcellulose (HPMC): refined cotton, methyl chloride, propylene oxide, and other raw materials, caustic soda, acid, toluene, isopropanol, etc.

8. What is the main function of the application of HPMC in putty powder, and does it happen chemically?

Answer: In the putty powder, HPMC plays three roles of thickening, water retention and construction. Thickening: Cellulose can be thickened to suspend and keep the solution uniform up and down, and resist sagging. Water retention: make the putty powder dry slowly, and assist the ash calcium to react under the action of water. Construction: Cellulose has a lubricating effect, which can make the putty powder have good construction. HPMC does not participate in any chemical reactions, but only plays an auxiliary role. Adding water to the putty powder and putting it on the wall is a chemical reaction, because new substances are formed. If you remove the putty powder on the wall from the wall, grind it into powder, and use it again, it will not work because new substances (calcium carbonate) have been formed. ) too. The main components of ash calcium powder are: a mixture of Ca(OH)2, CaO and a small amount of CaCO3, CaO+H2O=Ca(OH)2—Ca(OH)2+CO2=CaCO3↓+H2O Ash calcium is in water and air Under the action of CO2, calcium carbonate is generated, while HPMC only retains water, assisting the better reaction of ash calcium, and does not participate in any reaction itself.

9. HPMC is a non-ionic cellulose ether, so what is non-ionic?

Answer: In layman’s terms, non-ion is a substance that will not ionize in water. Ionization refers to the process in which an electrolyte is dissociated into charged ions that can move freely in a specific solvent (such as water, alcohol). For example, sodium chloride (NaCl), the salt we eat every day, dissolves in water and ionizes to produce freely movable sodium ions (Na+) that are positively charged and chloride ions (Cl) that are negatively charged. That is to say, when HPMC is placed in water, it will not dissociate into charged ions, but exist in the form of molecules.

10. Is there any relationship between the drop of putty powder and HPMC?

Answer: The powder loss of putty powder is mainly related to the quality of ash calcium, and has little to do with HPMC. The low calcium content of gray calcium and the improper ratio of CaO and Ca(OH)2 in gray calcium will cause powder loss. If it has something to do with HPMC, then if HPMC has poor water retention, it will also cause powder loss.

11. What is the gel temperature of hydroxypropyl methylcellulose related to?

Answer: The gel temperature of HPMC is related to its methoxy content, the lower the methoxy content↓, the higher the gel temperature.

12. How to choose the appropriate hydroxypropyl methylcellulose (HPMC) for different purposes?

Answer: The application of putty powder: the requirements are relatively low, and the viscosity is 100,000, which is enough. The important thing is to keep water well. Application of mortar: higher requirements, high viscosity, 150,000 is better. Application of glue: instant products with high viscosity are required.

13. What is the difference between the cold-water instant type and the hot-soluble type of hydroxypropyl methylcellulose in the production process?

Answer: The cold water instant type of HPMC is surface-treated with glyoxal, and it disperses quickly in cold water, but it does not really dissolve. It only dissolves when the viscosity increases. Hot melt types are not surface treated with glyoxal. If the amount of glyoxal is large, the dispersion will be fast, but the viscosity will increase slowly, and if the amount is small, the opposite will be true.

14. What is the smell of hydroxypropyl methylcellulose (HPMC)?

Answer: The HPMC produced by the solvent method uses toluene and isopropanol as solvents. If the washing is not very good, there will be some residual smell.

15. What is another name for hydroxypropyl methylcellulose?

Answer: Hydroxypropyl Methyl Cellulose, English: Hydroxypropyl Methyl Cellulose Abbreviation: HPMC or MHPC Alias: Hypromellose; Cellulose hydroxypropyl methyl ether; Hypromellose, Cellulose, 2-hydroxypropyl methyl Cellulose ether. Cellulose hydroxypropyl methyl ether Hyprolose.

16. What should be paid attention to in the actual application of the relationship between the viscosity and temperature of HPMC?

Answer: The viscosity of HPMC is inversely proportional to the temperature, that is to say, the viscosity increases as the temperature decreases. The viscosity of a product we usually refer to refers to the test result of its 2% aqueous solution at a temperature of 20 degrees Celsius.

In practical applications, it should be noted that in areas with large temperature differences between summer and winter, it is recommended to use a relatively low viscosity in winter, which is more conducive to construction. Otherwise, when the temperature is low, the viscosity of the cellulose will increase, and the hand feel will be heavy when scraping. Medium viscosity: 75000-100000 Mainly used for putty. Reason: good water retention. High viscosity: 150000-200000 Mainly used for polystyrene particle thermal insulation mortar glue powder and vitrified microbead thermal insulation mortar. Reason: high viscosity, mortar is not easy to drop, hang, and improve construction.

17. The application of HPMC in putty powder, what is the reason for the bubbles in the putty powder?

Answer: In the putty powder, HPMC plays three roles of thickening, water retention and construction. Do not participate in any reactions. Reasons for bubbles: 1. Put too much water. 2. The bottom layer is not dry, just scrape another layer on top, and it is easy to foam.